It is often necessary or desirable for a person to exercise a particular muscle or group of muscles. For example, when a muscle is damaged, such as through injury or surgery, it is important to exercise the muscle to prevent atrophy and to strengthen the muscle for normal use. Further, people exercise healthy muscles to increase strength and to maintain an active and healthy lifestyle, as well as to improve their appearance. Various routines have been developed to exercise different muscle groups by forcing the muscles to contract and extend under a load, such as by moving a free weight against the force of gravity or by moving a handle whose movement is resisted by an exercise machine.
One such exercise is known as a row exercise, where the latisimus dorsi muscles are exercised. An exerciser lies prone on a bench, or bends at the waist, and grasps a barbell below him. The exerciser then pulls the barbell towards his torso and lowers it down. This exercise can be dangerous as the exerciser may drop the barbell. Additionally, as the arms are drawn towards the torso, it is difficult to keep them low enough with respect to the trunk to involve the latisimus effectively. If the user pulls the bar towards the chest, the ability of the latisimus dorsi muscles to move the resistance decreases.
Furthermore, the exerciser should have a partner to spot him in case he fails to lift the weight. Even if done properly with a partner, this exercise may not permit the user a full range of exercise since the barbell may hit the user's chest before the back muscles have contracted fully. When using free weights, the resistance provided by gravity is constant while the strength of the muscles varies over the range of motion. Consequently, the muscles are not fully loaded at each point over the range.
To overcome these difficulties, machines have been developed that simulate the exercise movements of a row/rear deltoid exercise. In one apparatus, disclosed in U.S. Pat. No. 5,620,402, a user exercises by pulling handles toward his torso. A seat and chest pad are mounted to a frame to position a user. Arms are rotatably mounted to the frame. The handles are mounted to the arms. The pivot for the arms is disposed above the seat. A cable operably connects the arms to a weight stack such that when a user pulls back on the handles, thereby rotating the arms, the weight stack is lifted and provides resistance to the exercise. The cable may be journaled over a variable radius cam to alter the distance the weight is displaced for a given amount of handle rotation at a particular point in the range of motion. Consequently, the resistance to the movement of the handles can be varied to match the strength curve of the back muscles. Unfortunately, the combination of row and rear deltoid exercise requires compromise for both patterns. The rear deltoid exercise is best performed in a transverse plane. The row exercise is best performed in the sagittal plane. Most row/rear deltoid machines do not have enough vertical motion at the grip to allow for the full range of sagittal plane motion required to do the exercise correctly.
In another apparatus, disclosed in U.S. Pat. No. 5,135,456, a rowing machine is disclosed in which levers are rotatably mounted to a frame. Handles are mounted to the levers. Resistance to handle movement exercise is provided by weight plates mounted to the levers. The hinges for the levers are disposed at diverging angles with respect to a central vertical midplane, such that the user moves his hands in defined arcs in diverging planes as he pulls back on the handles. This apparatus forces the user's hands to be spread apart as the handles are drawn back toward the chest. The diverging motion is successful in greater engagement of the rear deltoid due to it's greater degree of transverse plane motion, but does not allow for enough vertical motion in the sagittal plane to do the row in a way that effectively engages the latisimus dorsi over the greatest range of motion.
It is object of this invention to provide an exercise machine which optimally isolates the latisimus muscle group to maximize muscular benefit during performance of a row movement.